Backmarker: The NS750 Flat Tracker

A few weeks back, I wrote about Motion Pro’s Chris Carter and his amazing personal collection of vintage motorcycles. I mentioned his ultra-rare Honda NS750 flat tracker and said it was worthy of a column in itself. Actually, after digging into it a little more, it’s worth at least two and a half. Anyway, let’s get started….

Most of Honda’s explosive sales growth in the U.S. market through the ’60s and ’70s was accomplished without a concerted or comprehensive AMA racing program. There were brief periods official interest, but somehow American Honda seemed immune to the racing bug, at least by comparison to the UK and European subsidiaries, and to RSC (Racing Services Corporation, the predecessor to today’s HRC) back in Japan.

But by the early ’80s, American Honda had to admit that Grand National Championship would be a marketing boon. That meant building a competitive flat tracker. Harley-Davidson had worked the bugs out of the XR750 over the previous decade and shown that V-twin power was the way to go.

It was easy to source a proven frame from one of the indie frame shops like C&J. That all made sense. What didn’t make any sense at all was any one from Honda looking at their CX500 and saying, “We’ve already got a V-twin, let’s race it.” Yes, they actually decided to race the “plastic maggot”—an underpowered, shaft-drive, transverse-V commuter bike that looked like a baby Moto Guzzi and was favored by London motorcycle couriers—in AMA Grand Nationals. That was like Road Racer X signing me up to fight in the UFC. Of course to have any chance of being competitive, they had to punch it out to the 750cc displacement limit. That was a bit like putting me on a heavy dose of steroids; it sounds kind of fun, but there were bound be complications.

According to AMA homologation rules, Honda had to build parts for twenty-five motors, but only five or six Honda NS750s were ever assembled. Privateers hardly clamored for them, since it was one of the rare factory Honda efforts that didn’t yield a winning bike.

The accepted wisdom has long been that the NS was a flop, and that for two years, Honda riders had their asses handed to them by guys on Harley-Davidson’s XR750; the one exception was Scott Pearson’s win on the Louisville half-mile.

As the story goes, Honda reverse-engineered a Harley XR750 to create the RS750. In his book Harley-Davidson Racing 1934-1986, Alan Girdler wrote, “…they’d bought an XR-750 engine, taken it home, and taken careful notes on it.”

The AMA Museum—in the none-too-flattering curatorial notes that accompanied the ex-Bubba Shobert championship-winning RS on display (a bike which, incidentally also belongs to Carter)—also suggested that Honda copied Harley-Davidson. The Museum wrote, “Honda’s air-cooled, V-twin, 749.5cc powerplant clearly benefited from close study of the Harley XR750, introduced in 1972. It is, for instance, no coincidence that the RS750 ended up with identical bore and stroke dimensions to the Harley—79.5mm x 75.5mm.”

Although the RS was a winner, Tolstoy was right, “Happy families are all alike; every unhappy family is unhappy in its own way.” When it comes to Hondas at least, I’m far more fascinated by rare failures. So after Carter’s NS750 piqued my curiosity, I sought out Jerry Griffith, who chopped and turned that CX500 motor to create the very first NS750 prototype.

Jerry was the hub of all of Honda’s factory efforts in Grand National flat track. He did everything from building motors to managing teams. He conceived the NS and then convinced Honda to build the RS. After talking to him, I realized that the NS’ reputation as a loser was an oversimplification, and that the RS’ reputation as a Harley clone—a smirch that I’ve helped to propagate myself—was flat wrong.

So what’s the truth? I thought you’d never ask….

Once again, a classic American racing story goes back to Kenny Roberts. The King and Jerry were partners in a motorcycle-frame business. Just before Kenny went to Europe, they built a little TZ250 flat tracker for Kenny to ride in Houston. After Kenny left, Jerry let Jeff Haney ride it at Ascot, and he started winning on it and just kept winning. He won every race that year.

Despite Haney’s impressive season, Yamaha didn’t want anything to do with them the next year, so they got an XR500 Honda dirt bike motor through Dave Bird, a dealer who was active in flat track, building and selling parts like exhausts.

Well, why don’t I just let Jerry pick up the story from there:

The frame was just a one-off frame I built for Jeff, with that 500 single motor. Jeff raced that in the Junior class at Ascot, against Harleys and everything, and he won every race he entered. So Honda started helping us. It was between us or Mickey Fay. He’d won Houston on a Honda, but we got lucky and they picked us. Honda also sponsored a special race for singles, and either Jeff or Mickey won every one of those. I’m going to say that was ’78 or ’79.

Dennis McKay, Honda’s race boss at the time, was really a dirt track fan, and he was wanting to get Honda into dirt track. We knew we couldn’t compete with the Harleys if we only had that single, but Honda didn’t have a 750 twin; they only had fours. So that [the CX500] was all we had to work with; it was a sorry deal. He gave me a CX500 motor. We turned it around sideways and grafted a sprocket on it.

We couldn’t turn the heads, so the guy’s leg had to go between the carburetors. It wasn’t real comfortable. Initially, we didn’t change the displacement. Honda was already making a turbocharged 600cc version, but they didn’t have one of those to give us. We thought that if we could at least get the 600 one, we’d get a little closer. The 500 had no power. It was at least 10 mph down on top speed; it really wasn’t competitive at all.

Mr. Irimajiri [the legendary HRC engineer who created the oval-piston NR500] came to the San Jose Mile in ’79 or ’80 and watched it run; he really liked it and got his picture taken sitting on it. The first thing you know, he built—well, we got hired by them—and he built five or ten of those engines. [By “those engines,” he means a bored and stroked CX500 engine displacing 750cc, converted from shaft to chain drive—MG]

We built the frames for them. We tried quite a few frames; the first ones had twin shocks, then we tried a monoshock. Once we got the chassis working, we sent it to C&J and they made, like, five of them.

It was a long-term deal trying to win with that thing. The two guys that helped the most to develop it were Ted Boody and Hank Scott. We’d go back east and run all those non-National miles from Kansas to Ohio.

At first, I was the mechanic, the pit boss, truck driver…. As it got bigger, I couldn’t handle all that stuff. They wanted me to be the crew chief, but then they wouldn’t have let me work on the bikes, so I talked them into hiring Gene Romero to be our crew chief. The mechanics that worked on the bikes with me were Dan Murrell, Dennis Jones, Dave Bird.

We started from scratch. When I raced, bikes didn’t even have shocks, so I learned from Kenny. I didn’t know nothing, but I knew enough to keep Jeff happy. I learned a lot from Hank and Ted Boody, they helped me a lot. Mike Kidd had a lot of input; so did Terry Poovey and Mike Pearson. Most of them didn’t like it!

The problem wasn’t a lack of power. In the end, we got 90-92 horsepower out of it. We were spending money trying to win. I did a lot of dyno work with it myself, but lots of other people helped too; I had Jimmy Dour at Megacycle, Jerry Branch built heads, Kenny Augustine…. But its biggest problem was that they’d bored it out so big, it didn’t have enough room [in the water jacket] around the sleeves. It would get steam pockets in it and overheat and slow down. We couldn’t run antifreeze; if we could have run antifreeze, it wouldn’t have boiled it out.

But it was a rocket for four or five laps. I mean, Hank once told me it was the best-handling bike he’d ever ridden, but… I think it ruined Jeff Haney’s career. He had tons of talent, but he got to the point where he had no confidence in it. I kept telling Jeff, “Have patience,” but he was just a young kid.

Mike Kidd took more of a professional approach. He had won the #1 plate on a Harley the year before, and he approached it like a job. Mikey was at the end of his career, and he’d already been there and done it all. But he got a lot done; we made a lot of finals. Everyone who was involved wanted to win, but to start out and beat them Harleys was not easy. They’d been winning forever.

The one time we won [a National, at the Louisville half-mile], it just fell into our hands. Scott Pearson won the last-chance qualifier, and they lined everyone up on the front row. Everyone got to pick before Scott, but there was a little hole right on the inside, on the pole, and Scott lined up there.

The groove at Louisville was only about three feet wide. If you tried to pass on the outside, you lost about five spots. Scott was such a holeshot guy that I said, “If you can get to the front, there’s no way they can pass you.” He just had that thing sideways for about twenty-five laps, and every time someone tried to pass him, they’d pull out and just go backwards. It was Scott Pearson that won the race, not the motorcycle.

So, I stand corrected. The NS750 wasn’t an abject loser. It handled well and was fast, just not fast enough for long enough. To make competitive power, Irimajiri had to bore the cylinders clean out of it and fit much larger sleeves. There were narrow spots where the sleeve constricted the flow of water in the water jacket, and steam formed there. As the temperature went up during the races, the bike went slower and slower.

Not withstanding Pearson’s one historic win on the NS, Griffith and Honda knew they needed to run something different to win that #1 plate. Come back to AGV Backmarker next Thursday; with Jerry’s help, I’ll shatter another old myth: that Honda copied Harley-Davidson’s XR750 when it made the RS750.